Application of clonal culture techniques to the direct isolation and culture of cells from normal autopsy specimens and from patients with benign hypertrophy or carcinoma of the prostate has yielded over 40 cell lines. These are preserved in liquid nitrogen. Although all lines examined have tartrate-inhibitable acid phosphatase, this property is not limited to cultures of prostatic origin. It is proposed to seek additional markers that may be useful in cell identification. The ability to bind, dependence upon, and response to androgens and other hormones will be studied in cultured cells.